Zugaib M, Forsythe A B, Nuwayhid B, Lieb S M, Tabsh K, Erkkola R, Ushioda E, Brinkman C R, Assali N S
Am J Obstet Gynecol. 1980 Oct 15;138(4):444-52. doi: 10.1016/0002-9378(80)90144-1.
The contributions of the intrinsic, beta-adrenergic, and cholinergic systems to the mechanisms of beat-to-beat variability of the heart rate were investigated in chronically instrumented, unanesthetized newborn lambs from the first week to the eighth week of neonatal life. During this period of neonatal growth, the resting heart rate decreased spontaneously every week; the decrease was not related to alterations in the sympathetic and parasympathetic tones but rather to changes in the intrinsic mechanisms of heart rate control. Despite the weekly decrease in the resting heart rate of the neonatal lamb, the long and short-term beat-to-beat variabilities did not change significantly. This finding suggests an absence of a significant influence of the intrinsic mechanisms of heart rate control on the genesis of beat-to-beat variability. The results obtained with the various modes of adrenergic and cholinergic blockades and stimulation seem to indicate that the autonomic nervous system contributes significantly to the appearance of beat-to-beat variability. However, the influences of the adrenergic and cholinergic systems differ from week to week of neonatal growth and the patterns of changes are not the same for the long-term and short-term variabilities. The implication of these studies in terms of physiologic and hemodynamic significance of beat-to-beat variability in heart rate is discussed.
在出生后第一周直至第八周的新生未麻醉羔羊身上，通过长期植入仪器的方式，研究了心脏固有系统、β-肾上腺素能系统和胆碱能系统对心率逐搏变异性机制的作用。在新生儿生长的这段时期内，静息心率每周自发下降；这种下降与交感神经和副交感神经张力的改变无关，而是与心率控制的固有机制变化有关。尽管新生羔羊的静息心率每周都在下降，但长期和短期的逐搏变异性并未显著改变。这一发现表明，心率控制的固有机制对逐搏变异性的产生没有显著影响。通过各种肾上腺素能和胆碱能阻断及刺激模式获得的结果似乎表明，自主神经系统对逐搏变异性的出现有显著贡献。然而，肾上腺素能和胆碱能系统的影响在新生儿生长的不同周数有所不同，长期和短期变异性的变化模式也不相同。本文讨论了这些研究对于心率逐搏变异性的生理和血流动力学意义的启示。
